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Master-Detail & indexes |
Tue, Sep 25 2007 5:05 AM | Permanent Link |
Joze | Hi,
I have a master-detail relation via TWO fields: MasterFields:='CustomerID; CustomerNAME'; What indexes should I have: solution A: #1 by CustomerID #2 by CustomerNAME like CREATE INDEX "CustomerID" ON "Customers"("CustomerID"); CREATE INDEX "CustomerNAME" ON "Customers"("CustomerNAME"); or solution B: #1 by CustomerID+by CustomerNAME like CREATE INDEX "MyCustomer" ON "Customers"("CustomerID","CustomerNAME"); Which one would work better? TIA for advice. Regards, Joze |
Tue, Sep 25 2007 9:08 AM | Permanent Link |
Chris Erdal | Joze <Joze.NoSpam.Stihec@nospam.siol.net> wrote in
news:d0jhf3hc58dktun9802roon040u83klp1k@4ax.com: > Hi, > > I have a master-detail relation via TWO fields: > > MasterFields:='CustomerID; CustomerNAME'; > > > TIA for advice. Joze, You may not like this advice, but you asked for it Assuming your CustomerID is unique in the Master table, just use it on its own and things'll be faster and simpler. Also, it is (almost) never, IMHO, a good thing to duplicate names etc in child tables - somebody always ends up mis-spelling the name e.g. when it's first inserted, noticing it in one table, correcting it there, and breaking the link if it was used in a master-detail relationship, or just getting confused next time they try to find both records together. I say almost because sometimes you really need to avoid lookups for extra speed when doing some lengthy processing, but that's probably a hangover from experience with Access - DBISAM's so fast it can cope. -- Chris (XP-Pro + Delphi 7 Architect + DBISAM 4.25 build 4 + EDB 1.04 build 3) |
Tue, Sep 25 2007 5:19 PM | Permanent Link |
Tim Young [Elevate Software] Elevate Software, Inc. timyoung@elevatesoft.com | Joze,
<< I have a master-detail relation via TWO fields: MasterFields:='CustomerID; CustomerNAME'; What indexes should I have: >> As Chris indicated, you should probably trim down the master table's index to just the CustomerID. It should be unique if it is being used as the ID for customers. Secondly, just use this index: #1 by CustomerID CREATE INDEX "CustomerID" ON "Customers"("CustomerID"); -- Tim Young Elevate Software www.elevatesoft.com |
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